Lesions causing aphantasia are connected to the fusiform imagery node

The absence of visual mental imagery, called aphantasia, occurs congenitally in up to 3% of the general population, but the brain regions responsible for aphantasia remain uncertain. Rare cases of acquired aphantasia caused by brain lesions may lend insight into the neuroanatomy responsible for this condition, and the neural substrate of visual mental imagery itself. We performed a systematic literature review to identify cases of lesion-induced aphantasia and traced the lesion locations onto a common brain atlas. These locations were compared to control lesions causing other neuropsychiatric symptoms (n = 887). First, we tested for intersection between lesion locations and an a priori region of interest termed the fusiform imagery node, active during visual mental imagery tasks. Second, we tested for connectivity between lesion locations and this region of interest, leveraging resting-state functional connectivity from a large cohort of healthy subjects (n = 1000). Finally, we performed a data-driven analysis assessing whole-brain lesion connectivity that was sensitive (100% overlap) and specific (family-wise error p < .05) for aphantasia. We identified 12 cases of lesion-induced aphantasia, only 5 of which intersected the fusiform imagery node. However, 100% of these lesion locations were functionally connected to the fusiform imagery node. Connectivity to this region was both sensitive (100% overlap) and specific (family-wise error p < .05) for aphantasia in a data-driven whole-brain analysis. Lesions causing acquired aphantasia occur in multiple different brain regions but are all functionally connected to the left fusiform imagery node. This study provides causal support for the importance of this brain region in visual mental imagery.